4. Question

Address of variable a is assigned to the integer pointer ptr.
Due to the statement;
*ptr += 1;
value at address pointing by ptr incremented by 1.
As the value at address is changed so variable a also get the updated value.

10. Question

* is a dereference operator & is a reference operator. They can be applied any number of times provided it is meaningful. Here p points to the first character in the string “C Programming”. *p dereferences it and so its value is C. Again & references it to an address and * dereferences it to the value C.